/**
 * 力扣：572 另一颗树的子树
 */
class Solution2 {
    public boolean isSubtree(TreeNode root, TreeNode subRoot) {
        if(root == null) return false;
        if(isSameTree(root,subRoot)) return true;
        if(isSubtree(root.left, subRoot)) return true;
        if(isSubtree(root.right,subRoot)) return true;
        return false; 
    }
     public boolean isSameTree(TreeNode p, TreeNode q) {
       if(p == null && q != null || p != null && q == null)   {
            return false;
        }

        if(p == null && q == null) {
            return true;
        }

        if(p.val != q.val) {
            return false;
        }

        return isSameTree(p.left,q.left) &&
                isSameTree(p.right,q.right);
    }
}